Publications
Enhancement of double-pipe heat exchanger effectiveness by using porous media and TiO2 water
Apr 1, 2023Journal CFD letters
Publisher SEMARAK ILMU
DOI 10.37934/cfdl.15.4.3142
Issue 4 (2023) 31-42
Volume 15
In this paper, the rate of heat transfer by forced convection in a counterflow heat exchanger, at turbulent flow conditions were investigated experimentally, using porous media and TiO2 Nanofluid to observe the behaviour of heat transfer with flow rate and volume concentration of nanoparticles t enhance heat transfer through it. 3 mm Steel balls (ε=39.12%) as a porous media completely filled to the inner pipe (core pipe). The cold and hot water are used as working fluids through the inner and outer pipes. Then using, the TiO2 nanofluid instead of cold water flowing through the porous pipe to enhance heat characteristics. The effects of operating parameters include flow rate (4 LPM, 6 LPM, and 8 LPM), Reynolds number between (3000 – 7000), and nanoparticle volume fraction (0.001, 0.002 and 0.003) on Convective heat transfer coefficient and Nusselt number. Effective thermal conductivity is increased when the nanoparticle volume fraction is increased. The heat transfer coefficient increases with decreasing nanofluid temperature, but the heating fluid's temperature has no significant effect on the nanofluid's heat transfer coefficient. The results show that porous media and TiO2-based nanofluid's improve heat transfer at flow rate of 4 LPM by 35.4% and improve NTU and effectiveness at flow rate of 4LPM by 12.4%, and 24%, respectively, when compared to pure water without porous media. This improvement in thermophysical properties yielded high heat transfer of heat exchangers used in process industries.
Thermodynamic analysis and optimization of flat plate solar collector using TiO2/Water nanofluid
May 10, 2023Journal Journal of Harbin Institute of Technology
Publisher Harbin Institute of Technology
DOI 10.11916/j
Issue 4,2024
Volume 31
To research solar energy''s efficiency and environmental benefits, the thermal efficiency, exergy, and entropy of solar collectors were calculated. The experiment involved two glass-topped collectors, fluid transfer tubes, and aluminum heat-absorbing plates. Glass wool insulation minimized heat loss. A 0.5% TiO2/Water nanofluid was created using a mechanical and ultrasonic stirrer. Results showed that solar radiation increased thermal efficiency until midday, reaching 48.48% for water and 51.23% for the nanofluid. With increasing mass flow rates from 0.0045 kg/s to 0.02 kg/s, thermal efficiency improved from 16.26% to 47.37% for water and from 20.65% to 48.76% for the nanofluid. Filtered water provided 380 W and 395 W of energy in March and April, while the nanofluid increased it to 395 W and 415 W during these months. Mass flow generated energy, and the Reynolds number raised entropy. The noon exergy efficiency for nanofluids was 50%-55%, compared to 30% for water. At noon, the broken exergy measured 877.53 W for the nanofluid and 880.12 W for water. In Kirkuk, Iraq, the 0.5% TiO2/Water nanofluid outperformed water in solar collectors.
Numerical study of heat transfer in circular pipe filled with porous medium
Mar 22, 2024Journal Pollack Periodica
Publisher Akadémiai Kiadó
DOI https://doi.org/10.1556/606.2023.00869
Issue 1
Volume 19
Forced convection heat transfer was studied in a horizontally heated circular pipe with constant heat flux. Porous medium was created using 1 and 3 mm stainless-steel balls (porosity: 0.3690 and 0.3912). Reynolds numbers ranged from 3,200 to 6,500 based on pipe diameter, with heat flux rates of 6,250 and 12,500 W m−2. ANSYS Fluent simulated a 51.4 mm diameter, 5 mm thick, 304 mm long stainless-steel pipe. Results showed increased turbulence and eddy formation. Analysis revealed higher convective heat transfer coefficient, pressure drop, and Nusselt number with increasing Reynolds number. Nusselt number also increased with 1–3 mm ball diameter. 6% porosity increase reduced pressure drop by 84.4%. Nusselt number rose by 46.7% (Reynolds 3,200–6,500) and 4.36% (heat flux 6,250–12,500 W m−2).